Single element transducers can be mounted to a distal end of a probe for invasive imaging of blood vessels or cavities within the human body. By sending a voltage signal to the two electrodes of the transducer, a piezoelectric material within the transducer is excited and generates acoustic signals. The same piezoelectric material can also convert acoustic signals reflected from an object into voltage signals. The transducer may be assembled to a cable to form a forward looking probe, that is, a probe for imaging in the same direction as the longitudinal axis of the cable. The forward looking probe can be used in applications such as rectal imaging. Alternatively, the transducer may be assembled to a cable to form a side looking probe. By rotating the side looking probe along its longitudinal axis, a plane perpendicular to the longitudinal axis of the probe can imaged. The side looking probe can be used in applications such as intravascular imaging. Multiple single element transducers may also be assembled into a sparse array (such as a basket type array) for applications such as mapping a heart chamber. Since the ultrasound probes are designed for invasive imaging, miniaturized ultrasound transducers may be utilized.
Wiring the two electrodes of the transducer to the cable can be challenging due to the small size of the transducer. One approach is to attach one electrode of the transducer to a substrate having a printed circuit, and manually apply silver epoxy to connect the other electrode to the substrate. However, this process lacks reproducibility and robustness. Since silver epoxy has high viscosity, it is difficult to manually apply a controlled amount of epoxy. Silver epoxy also lacks robust adhesion to the substrate due to its high sensitivity to moisture and long curing time. Further, due to long touch time and cycle time, the process is not suitable for manufacturing disposable probes.